The present invention relates to the field of dental equipment. More specifically, this invention is concerned with portable dental tools for either cleaning the tooth surface or cutting away or abrading selected portions of the tooth, depending upon the type of abrasive.
Dental hand pieces traditionally are used for cleaning and abrading the surface of teeth through a combination of an abrasive medium and a liquid delivered to the surface of the teeth. Commonly, the hand pieces have a nozzle through which a gas stream, typically air, with powdered abrasive contained therein is delivered to the tooth area. To effectively clean teeth with abrasives, the pressure of the gas delivering the abrasive must be of a substantial strength to remove foreign materials such as plaque, stains, and minor calculus deposits. The liquid, typically a medicated or antiseptic aqueous solution, is used to reduce the plume of rebounding abrasive material and dental material and keep the tooth area free of extraneous material.
The use of abrasives in the area of dentistry has been long known. Abrasives have been used for either removing foreign materials such as plaque, stains, and calculus deposits from the surface of human teeth without damage to the enamel, or cutting away of tooth material comprising caries in preparation for fillings of various types. Abrasive materials employed in the cleaning process have generally been either water soluble compounds such as sodium bicarbonate (NaHCO3) or water insoluble compounds such as aluminum oxide (Al2O3). The standard abrasive process employs an abrasive-laden gas stream having particles of the abrasive material suspended therein and a liquid at high pressure. The two streams are either combined prior to directing them to the tooth surface or directed separately to the tooth surface where they interact.
For example, U.S. Pat. No. 4,878,320, entitled xe2x80x9cAbrasive Feed Systemxe2x80x9d, to Woodson, discloses such a system using water-soluble sodium bicarbonate suspended in nitrogen gas for the removal of a covering or coating of a material to be cleaned without damaging the underlying substrate.
However, the use of abrasives within a high pressure system has attendant problems associated with such use. First, the abrasive tends to rapidly abrade the interior of the nozzle directing the abrasive stream to the tooth and the channel through which the abrasive-laden gas travels, necessitating the reworking and replacement of various parts of the handpiece, nozzle arrangement, and the abrasive system in general. This abrading action is particularly problematic for abrasive systems having 90xc2x0 or other relatively sharp bends in the gas channel, since the abrasive more rapidly wears the interior or the channel at those points of sharp curvature.
Second, channels often clog with precipitate formed in systems that either internally mix abrasive material and water prior to expelling the mixture or else allow a portion of an expelled abrasive-laden gas stream to be drawn back into the water or gas channels. Abrasive systems in general have minute orifices through which the abrasive-laden stream is tightly focused on a selected area of the tooth. The dry abrasive, when combined with a liquid such as water, tends to clog these small orifices. Complicated and detailed arrangements have been proposed to prevent clogging and ensure a self-cleaning aspect to the abrasive system.
Third, portions of the dental system, and the handpiece in particular, must be autoclaved to prevent the spread of bacteria from patient to patient. The handpiece must be disassembled for use in the autoclave so that all parts may be treated. Some parts of the handpiece are not autoclaved since they do not come into direct contact with the mouth area and may be cleaned by using an alcohol wipe.
Fourth, it is often the case that a person using an dental abrasion system is required to use a water-soluble abrasive for cleaning of teeth and then must switch to a water insoluble abrasive to fix a cavity. Most dental abrasion systems are configured for a single handpiece, a single set of gas/liquid channels, and a single abrasive reservoir. The system must be disassembled and cleaned when changing the type of abrasive. This results in loss of time and increased expenditure of effort.
Fifth, the systems and apparatus in current use are all contemplated for use with human operatories and are not suitable for veterinary use such as equine operatories. When such system are configured for veterinary use, they must frequently be taken into areas remote from electrical and water connections, such as pastures or barns where horses are typically found.
A number of systems have been proposed to address and correct these inherent problems. As one example, U.S. Pat. No. 4,984,984 to Esrock, discloses a system that contemplates replaceable nozzle heads as a solution to the stress and maintenance of abrasion delivery. Esrock also addressed issues of cleaning and sterilizing the system when combining water and the abrasive medium.
As can be seen, there is a need for a dental abrasion system having a durable handpiece with longer intervals between maintenance, better resistance to clogging of gas and water channels by the abrasive material, ability to be autoclaved, and flexibility for use with multiple abrasives without undue down time. Furthermore, there is a further need for a portable system that can be adapted for use in areas without a dependable power or water supply. Such a system should be adaptable for veterinary use, in particular, for use with equine stock.
In one aspect of the invention, a handpiece for use in an abrasion system is provided. The handpiece may be used by an operator to conveniently direct a pressurized abrasive-laden gas stream and a pressurized liquid stream as separate streams to a work area. The handpiece may comprise an elongate handle sized to gripped by a hand of an operator. The handpiece may further comprise a head assembly for attachment to a first end of the handle. The head assembly may have a nozzle protruding a distance from the head assembly for directing the abrasive-laden gas stream emanating from a tip of the nozzle to the work area, and it may also have an orifice directing the pressurized liquid stream to the same work area. A gas channel may be provided to receive the pressurized abrasive-laden gas stream at a second end of the handle and direct the pressurized abrasive-laden gas stream through the handle and the head assembly to exit the nozzle. A liquid channel also may be provided to receive the pressurized liquid stream at the second end of the handle and direct the pressurized liquid stream through the handle and head assembly to exit the orifice.
In another aspect of the invention, an abrasion system provided for the purpose of abrading a work area, the system comprising a a pressurized gas stream, a pressurized liquid stream, and a means for entraining a first abrasive material in the pressurized gas stream to produce an first abrasive-laden gas stream. First and second handpieces are also provided, the first handpiece simultaneously directing the first abrasive-laden gas stream and the pressurized liquid stream to the work area, so that the resulting plume of material emanating from the work area resulting from the first abrasive-laden gas stream is reduced. The second handpiece may be either a handpiece similar to the first handpiece or a dentist""s drill powered by the pressurized gas stream.
In yet another aspect of the invention, a mobile abrasion system is provided, the system having a gas tank providing a pressurized gas stream comprised of nitrogen gas and a water tank providing a pressurized liquid stream, the water tank receiving pressure from the pressurized gas stream. A first reservoir containing a first abrasive material is also included, where the first reservoir receives the pressurized gas stream, entrains the first abrasive material within the pressurized gas stream, and provides a first abrasive-laden gas stream. Two handpieces are also provided. The first handpiece receives the first abrasive-laden gas stream and the pressurized liquid stream and delivers the streams to the work area. The second handpiece also receives the pressurized liquid stream. If the second handpiece is for abrasive work, then a second reservoir containing a second abrasive material is also included, where the second reservoir receives the pressurized gas stream, entrains a second abrasive material within the pressurized gas stream, and provides a second abrasive-laden gas stream to the second handpiece, which then delivers both streams to the work area. If the second handpiece is a dentist""s drill, then the second handpiece receives the pressurized gas stream to operate the drill. A switch is provided to alternatively enable the first abrasive-laden gas stream and the pressurized liquid stream to flow to the first handpiece and enable the pressurized liquid stream to flow to the second handpiece, wherein the nonselected handpiece is disabled from the streams. The switch will also enable the second abrasive-laden gas stream to flow to the second handpiece when it is of same construction as the first handpiece. Finally, a foot pedal is provided for the operator to control the flow of the pressurized gas stream by alternatively enabling and disabling its flow, whereby the selected handpiece may be provided with liquid and gas streams at the option of the operator.